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Kinetics of the Microbial Degradation of 2,4‐D in Soil: Effects of Temperature and Moisture
Author(s) -
Parker L. W.,
Doxtader K. G.
Publication year - 1983
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1983.00472425001200040024x
Subject(s) - moisture , loam , water content , chemistry , activation energy , degradation (telecommunications) , decomposition , kinetics , bar (unit) , soil water , environmental chemistry , soil science , environmental science , geotechnical engineering , geology , organic chemistry , telecommunications , physics , oceanography , quantum mechanics , computer science
The effects of soil moisture tension and temperature on the kinetics of the degradation of (2,4‐dichlorophenoxy)acetic acid (2,4‐D) in an Ascalon sandy loam were studied under laboratory conditions to develop a simulation model. Degradation occurred by a slow, first‐order reaction (slow phase) which, under some conditions, was followed by a rapid, first‐order reaction (fast phase). The optimum temperature and moisture tension were 27°C and 0.1 bar, respectively. Degradation rates under optimum conditions were 0.230 and 2.234 µ g g −1 soil for the slow and fast phases, respectively. At temperatures above the optimum, no fast phase was observed. The activation energy ( E A ) values increased from 22.96 to 45.46 kcal mole −1 , with increasing soil moisture tension in the range from 0.1 to 1.0 bar. The rate of decomposition of 2,4‐D decreased with increasing soil moisture tension for temperatures between 20 and 35°C. This decrease was a result of the reduced activity of the 2,4‐D‐degrading microorganisms arising from decreased water availability and increased 2,4‐D solution concentration.